Corrosion-resisting metal article and method of making same.



W. J. MERTEN. CORROSION RESISTING METAL ARTICLE AND METHOD OF MAKING SAME.

APPLICATION FILED IAN.4. I918.

1 ,280,268, Patented Oct. 1, 1918.

E 14 ue mfoz M l l l t WILLIAM J. MERTEN, 0F PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO GEORGE D. BRECK, 0F CLEVELAND, OHIO.

} CORROSION-RESISTING METAL ARTICLE AND METHOD OF MAKING SAME.

Specification of Letters Patent.

Patented (let. 1-, 11918.

Application iiled January 4, 1918. Serial No. 210,362.

To all whom it may concern:

Be it known that 1, WILLIAM J. MERTEN, a citizen of the United States, residing .at Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a certain new and useful Improvement in Corrosion-Resisting Metal Articles and Methods of Making Same, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings.

This invention relates to a method of treating certain articles of iron or steel whereby their resistance to corrosion or oxidation by the action of different adverse agencies acting upon their respective surfaces may be augmented; and also relates to and includes certain articles and types of articles so treated and in which my inven-. tion is embodied. Many expedients for inhibiting the rustlng of iron have hitherto been suggested, but most of these have been restricted to articles which are normally used in a cold condition, as in the case of all machines and structural materials, while very few expedients have been found for protecting iron or steel whose normal use is in the heated condition as is the case in stoves, furnaces, boilers, superheaters, economizers, pipes, valves, etc., especially in cases where the two sides of the article are exposed to different oxidizing conditions, as, for example, the parts of a steam boiler; where one side is in contact with heated water and the other with furnace gases.

The objects of my invention are: the provision of a new and improved method of treatlng devices of the character described for the purpose of enhancing their resistance to the corroding conditions to which they are respectively subjected; the provision of a method of treating the respective surfaces of such devices as to obtain the maximum protective character of each and wherein the treatment of the one side shall have no inimical effect upon the condition or treatment of the other side; the provision of such a combination of protective expedients that each shall be peculiarly suited to withstand the conditions to which it is exposed throughout the entire temperature range'normally encountered in use; the provision of a protective method of such cheapness and conven- -ience as to be susceptible of widespread use;

the provision of certain articles and classes of articles superior to any previously known as regards their resistance to differing corrosive tendencies on their opposite sides; while further objects will appear as the description proceeds.

I have discovered that any treatment which will be adequate at a given elevated temperature must be applied at a still more elevated temperature; and that if differing hot treatments are to be applied to different parts or sides of the article in question, those treatments ought to be applied simultaneously in order to prevent the separate application of one treatment from either injuring theuntreated portion of the article or damaging the treatment already applied; the

corollary of these propositions being that the two diflering treatments should be such that both are most effectively performed at substantially the same elevated temperature.

As an example and not as a limitation of my invention, I may treat the one surface of a pipe, tube, valve, sheet, box, plate, or receptacle by the process known as sherardizing, simultaneously treating the opposite surface of the article in a mode to produce thereon a coating of magnetic oxid. In the case of a tube, box, or receptacle which is to have moisture on the inside, as in a water tube boiler, steam chest, superheater, economizer, or the like, the sherardized surface will be inside and the oxidized surface outside; in i the case of the flues of a fire tube boiler the treatments would be reversed. And whatsuitable metal or alloy, close the ends,

and raise the whole to a low red heat, under oxidizing conditions, subsequently cooling slowly in a non-hydrating atmosphere. The desired production of magnetic oxid on the exterior of the tube takes place at approximately the same temperature as does the adherent zinc-iron (or other alloy) coating on the interior, and both coatings will be permanent under all normal conditions of use lltl ' scribed; and it is wholly unimportant outside of these limits, what those processes are or whether they be new or old.

As another example, I may treat the one 'side of the article by a hot galvanizing process, or may coat the same by dipping in molten tin or zinc simultaneously with sherardizing, oxidizing or otherwise coating the other side; or I maycoat the interior and the exterior with different molten metals or The invention is also applicable to metals other than iron, though of less importance in other connections. I

In the drawings accompanying this appli.. cation, which are to be read in an illustrative and not a limiting sense: Figure 1 is a sectional diagrammatic view of part of a steam-generator embodying my invention;

Fig. 2 is a view showing a step in my process; and Fig. 3 is a view of a different type of article embodying my invention.

In Fig. 1, 1 represents the tubes of a water tube boiler, 2 the header, 3 the steam reservoir, 4 the superheater, and 5 the steam pipe, all of which are sherardized interior-fly and coated with magnetic oxid exterio'rlyfl' as described. 6 represents a steam valve w 'ose interior is sherardized and whose exteri' r is' not galvanized.

In Fig. 2, 10 represents the tube which is being treated, and 11, 11, the caps by which the ends are closed and the two treatments ke t apart.

ig. 3 represents a culinary or other vessel made of iron and having for example, a cadmium-silver lining and a copper-zinc .exterlor coating,'the two alloys having approximately the same melting oints.

It will be understood that tlie foregoing descriptionis illustrative rather than limitmg and that many changes may be made and numerous articles and treatments included within the sec e ofmy invention.

Having thus descri edmy invention what I claim is:-

1. The art of treating iron articles whose opposite sides are subjected to diverse corroding influences which consists in subjecting those-sides simultaneously to difi'erent corrosion inhibiting processes which require for their performance substantially the same elevated temperature.

2. The art of inhibiting corrosion in metal articles whose different parts are subjected to difierent corroding influences, which consists in subjecting those parts simultaneously to two unlike hot processes, each of whichis adequate to. inhibit the corroding effect of the particular influence an ticipat'ed and both of which require approximately the same elevated temperature for their performance. Y

3. The art of inhibiting corrosion in iron articles whose opposite sides are subjected to heat and moisture respectively which consists in applying to the one side a hot surface treatment peculiarly resistant to moisture-corrosion and to the opposite side a-hot surface, treatment peculiarly resistant to heat corrosion, said treatments being of natures requiring substantially the same elevated temperature for their performance.

' 4. The art of inhibiting corrosion in iron -articles whose opposite sides are subjected to heat and moisture, respectively, as in steam generating apparatus, which consists in applying comminuted zinc to that surface which is to be subjected to moisture, heating the article so that its opposite side is exposed to oxidizing conditions to a temperature sufficient to melt the zinc,

v and finally cooling the tube.

5. As an; article of manufacture, a hollow metal articl'e'ihaving upon its opposite sides a pair of dissimilar coatings whose application requires approximately the same elevated temperature.

6. As an article of manufacture a'hollowiron article having one of its surfaces sherardizedand its opposite surface covered with magnetic oxid.

In testimony whereof I hereunto afiix my signature.

WILLIAM J. MERTEN. 

